Method of and apparatus for separating the soft rock component of mixtures of hard and soft rock



2,736,502 ROCK 1956 H. A. TOULMIN, JR

METHOD OF AND APPARATUS FOR SEPARATING THE SOFT COMPONENT OF MIXTURES OF HARD AND SOFT ROCK Filed Sept 12, 1952 INVENTOR.

HARRY A. TOULM'NJR. BY

ATTORNEYS United States atent C N ETHOD OF AND APPARATUS FOR SEPARATING THE SOFT ROCK COMPONENT OF MIXTURES OF HARD AND SOFT ROCK Harry A. Toulmin, Jr., Dayton, Ohio, assignor to The Commonwealth Engineering Company of Ghio, Dayton, Ohio, a corporation of Ohio Application September 12, 1952, Serial No. 309,167

7 Claims. (Cl. 241-44) This invention relates to method and apparatus for processing a combined mixture of hard and soft rock with the view to the dual purposes of separating the hard rock from the soft rock and converting the soft rock into usable material.

It has long been a problem of the construction industry in connection with the manufacture of cement and the manufacture of highways where rock is mixed With asphalt, tar, and other road materials, to eliminate the soft rock cheaply and quickly, as well as continuously, leaving only the hard rock. The problem of the soft rock disposition has been that, in periods of heavy freezing or heavy loads in connection with concrete, the presence of the soft rock leads to weakening in unexpected places of the-concrete structure.

There are a variety of other reasons why the elimination of the different chemical and physical materials known as soft rock from the hard rock has been a problem. The term soft rock" isa misnomer in that such rock is softer as compared to the harder rock but it is in reality a very tough material. It resists much of the damage that is normally done to soft material because of its tenacious character and its firm composition. its cornposition is apparently cementitious and highly adherent. It is somewhat lighter in weight than the harder rock which is impervious, nevertheless there is not the sufficient difference to bring about any success by way of flotation separation, crushing etc. Likewise, there has been no success in centrifugal separation. The heating of the two rocks has led to no successful results as both of them are highly resistant to the effect of heat.

The price of hard rock alone is materially higher than a combination of hard and soft rock which is normally found mixed in nature where the rock is mined. The inclusion of the soft rock reduces the overall price of the combined hard and soft rocks; and there has been no way in which this soft rock could be successfully eliminated and no, way by which the resulting soft rock product could be utilized for other purposes.

The object of the present invention is to provide a continuous, simple, cheap and effective means of accomplishing two objects; first, to accomplish a clean, perfect separation of the soft rock from the hard rock irrespective of the variation in size; and secondly,v to put the soft rock in such new physical form that it can be readily used as a re-inforcing agent in connection with concrete blocks and material of that character because the present supply of cindersis disappearing and the demand for re-enforcing for concrete blocks of cheap kind. and quality is increasing.

Referring to the drawings the Figure 1 is a sectional view, schematically shown, of the complete mechanism of the process for treating soft and hard. rocks in suitable conditions for separation, disintegration and delivery in seperate form.

Figure 2 is a diagrammatically sectional view through a hard rock.

Figure 3 is a similar sectional view through a soft rock.

Figure 4 is an isometric perspective of the mechanism of Figure 1.

Figure 5 is a perspective partially in section showing the use of the hard rocks in a ball mill without balls, for reducing the soft rocks to a powder after the soft rocks have been completely treated, according to this process.

The mechanism.The mechanism consists of one or more conveyer belts delivering the combined soft and hard rock indicated at 1 into a hopper 4. The hard rock is designated as 2 and the soft rock is designated 3. This hopper is arranged to discharge at the bottom, after the hard and soft rock have been soaked for a period in the liquid indicated at 5 in the tank 4. The nature of this liquid and its action in connection with the rest of the process and in'connection with the hard and soft rock is described more fully hereinafter under liquid treatment.

This liquid is delivered as at 6 from the pipe 7 through which the liquid is being pumped by the pump 8 driven by the motor 9 from the tank 12 which contains the storage stock of the liquid 10. The liquid 10 is removed from the tank 12 by the pipe 11.

It will be observed that, when the combined hard and soft rock that issues from the soaking tank 4 falls as at 15 upon the Wire, the surplus fluid can drain off into the tank 12 and be reused in a continual cycle. The rock may be Washed of its remaining surface liquid of the liquid treating bath 5 by the water spray 19 from the water pipe 20. The liquid treated rock is then delivered to the chute 22, into the interior of the rotary kiln 23 which is closed at one end partially by the baffle plate 21 and the other end by the discharge plate 23a. The kiln 23 is rotated by a motor 24 driving the pinions 25 engaging the bull gears 26. The rotary kiln is supported on bearings at 27.

A pipe 28 supplies gas or oil for a burner at 29 having the burner openings 30 to supply intense heat through the interior of the kiln. At this point it is preferable to subject the rocks, as they rotate, to a temperature from 1200" F. to 1800" F., 1600 F. having been found very satisfactory. This temperature does not affect the hard rock, but it results in softening the soft rock and bringing about its disintegration, due to the absorption of the liquid, which has been absorbed into the soft rock, but does not affect the hard rock. The subsequent application of heat to the mixture of rocks comprising the soft rock containing the absorbed liquid results in physical disintegration of those soft rocks, without affecting the hard rock.

In the event that any of the soft rock has not completely disintegrated, this operation is completed by the discharge of the combined rocks upon the bounce plate 31 when the door 23a is opened for discharge. The bounce plate is located some distance below the discharge opening of the rotary kiln 23. The result is that the soft rock dust and the untouched hard rock discharge on to the screen 35 which is vibrated through the agency of the motor 32, gear train 33, vibrator 34, being supported at one end by the movable support, 36. The fine dust drops down upon the, conveyer belt 37, moving over the actuating rollers 38, while the hard rock is discharged on to the conveyer 39 supported on the rolls 40. In this way the relatively large aggregates of hard rock go in one direction and the soft rock dust is sent in another direction for further use.

Alternately, a tumbling barrel can be employed as shown in Figure 5 for the purpose of utilizing the hard rock as in a ball mill to crush and pulverize the soft rock at the chemical treatment. It will be understood that such a treatment has been impractical heretofore 3 because the soft rock has been so hard and tenacious and adherent in its material that it has been impossible to separate t e two rocks or crush the softer rock with the harder rock by mere tumbli g or ball mill operation.

However, after the liquid tree..-

and the heating step as heretofore indicated using apparatus as in Fig. 1, it is possible to utilize the hard rock to finish the separation of soft rock. This may be done directly, in some instances, without the necessity of the heating step.

The tumbling barrel 4i mounted upon the shaft has a cover 4-3 and is agitated by the motor 44-. When the operation is completed it c n be tilted and discharged onto the screen 35 which is vibrated by the vibrator 34, as heretofore described, and the hard rock remains on top of the screen while the crushed soft rock passes through the screen 3:"; onto the conveyor 37 supported on the roll Liquid treatment.-The applicant has found that the soft rock is relatively coarse and porous as compared to the hard rock which is dense and homogeneous. Therofor,-the porous soft rock will absorb, over a considerable period of time, water containing certain chemical agents and thereafter, when the hard and soft rocks are heated at a temperature of approximately 1609" F. in a rotary kiln, or furnace, the hard rock is not affected, but the disintegration of the porous soft rock is accomplished because at that stage, after absorption of the aqueous medium containing the chemical agents and on heating to the softening temperature for the soft rock while subjecting it to the tumbling and rollin operation in the kiln which, as shown, is supported with its longitudinal axis inclined slightly from the horizontal, the porous soft rock will disintegrate, the disentegration resulting from the heating being accelerated and facilitated due to the impact of the hard rock upon the porous softer rocks.

Typical examples are as follows:

Example I Triton X-200, the chemical composition of which is stated hereafter, was introduced into water to the extent of /2 of 1%. The hard and soft rocks were then dumped into tank 4 and left to soak. The mixture may be agitated while being soaked. If agitation is employed, the reaction will take place at greater speed. Also, the application of heat through this solution will accelerate the reaction and reduce the time of treatment. According to the type of rock, the concentration of the chemicals and the temperature and stirrin' conditions, the time of treatment will range from a few minutes to 24 hours. In the interest of economy, it is desirable to permit the soft rock to soak with the hard rock for about 24- hours unless faster production is required.

No apparent change in the dense hard rock result from this chemical treatment, but the softer rock absorbs, through at least a portion of its body, the water containing the Triton X2()0 with the result that when the combined rocks pass to the kiln, where the temperature is presently about 1600 F, and the rocks are rotated and tumbled within the kiln, it is possible to secure, upon discharging of the load of rocks, a hard rock untouched and a soft rock in the form of a fine, granulated powder.

Example 11 By utilizing Triton X-20tl, the chemical composition of which is stated hereinafter, to the extent of /2 of 1%, in water with the usual 24 hours soak, and using a number 6 hp neutral flame acetylene torch the soft rock disintegrates readily without spalling.

Example II! It has been found that when the mixture of hard and soft rocks is given a 24 hours soak in a medium made up by dissolving /2% of dry DuPonal ME in water treatment of the soaked mixture with a number 6 tip neutral flame acetylene burner has the result that the soft rock becomes very soft and breaks easily on shock.

4 Example IV Using either Triton X-200 or DuPonal ME, or a mixture of both, at about a total of /2 of 1% in water, and subjecting the samples to the furnace temperature of approximately 1600 R, it was found that in placing the combined hard rock and soft rocks so treated in a ball mill, without balls, that the hard rock would disintegrate the soft rock, in which the treatment with the aqueous solution had taken effect but had not affected the hard to t. rock without damaging the hard rock so that sep ration could be readily effected in the usual manner as described herein.

Triton X200 is a polyethylene oxide alkylphenol ether.

DuPonal" MB is a high molecular weight fatty alcohol sulphate.

it will be understood that I desire to comprehend within the. scope of the hereinafter appended claims such variations in mechanism, variations in processes and chemical materials used, as may be within the skill of the art of engineers, chemists, and physical chemists, so long as the general principles of this invention and the essentials of the discovery are retained.

I claim:

1. The method of separating soft rock in the form of particles of relatively small size from a mixture comprising soft and hard rocks in the form of aggregates of relatively large size which comprises soaking the mixture in an aqueous medium containing a wetting agent, removing excess soaking medium from the mixture, subjecting the soaked mixture to dry heat to bring it to the softening temperature for the soft rock while simultaneously continuously tumbling the mixture to thereby effect disintegration of the soft rock into particles of relatively small size and leave the hard rock in the form of aggregates of relatively large size, and thereafter separating the relatively small soft rock particles from the hard rock aggregates.

2. The method of separating soft rock in the form of particles of relatively small size from a mixturecornprising soft and hard rocks in the form of aggregates of relatively large size which comprises soaking the mixture in an aqueous medium containing a wetting agent, removing excess soaking medium from the mixture, subjecting the soaked mixture to dry heat to bring it to a temperature of 1200 F. to 1800 F. while simultaneously continuously tumbling the mixture to thereby effect disintegration of the soft rock into particles of relatively small size and leave the hard rock in the form of aggregates of relatively large size, and thereafter separating the relatively small soft rock particles from the hard rock aggregates.

3. The method according to claim 2 characterized in that, after the heating, the mixture of hard rock aggregates and relatively small particles of soft rock resulting from the soaking and simultaneous heating and continuous tumbling is subjected to additional agitation whereby the relatively small soft rock particles of the mixture are further disintegrated into particles of still smaller size.

4. The method according to claim 3, characterized in that, after the heating, the mixture of hard rock aggregates and relatively small particles of soft rock resulting from the soaking and simultaneous heating and continuous tumbling is subjected to additional agitation whereby the relatively small soft rock particles are reduced to dust.

5. The method according to claim 2 characterized in that the relatively small particles of soft rock resulting from the soaking and simultaneous heating and continuous tumbling are separated from the mixture thereof with the hard rock aggregates under conditions of agitation resulting in further reduction in the size of the soft rock particles during the separation.

6. The method according to claim 2, characterized in that, after the simultaneous heating and continuous tumbling, the resulting mixture of hard rock aggregates and The result was the pulverizing of the softer relatively small soft rock particles is tumbled in a ball mill, in the absence of balls, to effect further disintegration of the soft rock particles under the impact of the hard rock aggregates thereon.

7. Apparatus comprising, in combination, a soaking vessel having inlet and discharge openings therein, an endless non-reticulated conveyor supported for continuous travel adjacent the inlet opening of the vessel for feeding material carried thereby into the vessel, a rotary kiln arranged with its longitudinal axis inclined slightly from the horizontal and having a flame supported therein and inlet and discharge openings, an endless reticulated conveyor supported for continuous travel between the discharge opening of the soaking vessel and the inlet opening of the kiln for feeding material delivered from the soaking vessel into the kiln, means for continuously rotating the kiln, a bounce plate supported below and adjacent the discharge opening of the kiln, a reticulated member sup- 6 ported adjacent the bounce plate and arranged to receive material bouncing ott said plate, and a non-reticulated endless conveyor supported for continuous travel below the reticulated member for receiving material passing through the reticulated member.

References Cited in the file of this patent UNITED STATES PATENTS 46,620 Ayer Mar. 7, 1865 1,310,939 Bancroft July 22, 1919 1,311,645 Foss July 29, 1919 1,921,306 Aldrich Aug. 8, 1933 2,019,062 Thompson Oct. 29, 1935 2,078,933 Dean May 4, 1937 2,159,909 Price May 23, 1939 2,172,076 Wolf Sept. 5, 1939 2,360,518 Scripture Oct. 17, 1944 

